From the Kodokan and the Japanese Olympic Committee.
Kano Jigoro was born in 1860 in Mikage, in today’s Kobe. He was weak as a boy and trained in jujutsu to become strong.
He learned the Tenjin Shin’yo-ryu and then the Kito-ryu schools of jujutsu. He also studied other schools, took the good points of each, and added his own ideas to build a new system.
Kano taught the idea of using the power of body and mind most effectively, in the phrase seiryoku zenyo. He said its aim should be jita kyoei, helping oneself and others grow together.
Because the main goal was not the technique (jutsu) but a way (do) of perfecting oneself, he named it judo. The name Kodokan means a place to study the way.
Kano became the first member of the International Olympic Committee from Asia, and founded the body that is now the Japan Sport Association.
The International Judo Federation says judo was founded in 1882 by Kano Jigoro, and became an official event for the first time at the 1964 Tokyo Olympics.
There is no single right answer. Talking it over with someone at home is a good way to learn.